Samurai Sudoku rules

I’ve been asked a few times to post some Samurai sudoku solving tips. Well – there aren’t any special tips that apply exclusively to Samurai. Standard Sudoku rules apply, but to make things clear for newcomers, I’d like to give a brief set of instructions.

Rules of Samurai Sudoku

1. Each Samurai Sudoku puzzle consists of 5 overlapping classic 9×9 Sudoku sub-puzzles.
2. Each 9×9 sub-puzzle must be solved according to the rules of Sudoku: each row, column and 3×3 box must contain all digits from 1 to 9; therefore, digits cannot be repeated.
3. Each Samurai Sudoku puzzle has one solution only.

Warnings:

1. DO NOT ATTEMPT to completely solve each sub-puzzle as an individual puzzle!
2. Each 9×9 sub-puzzle when solved individually could have more than one solution.
3. Never resort to guessing my puzzles can be solved using deduction logic.

Solving suggestions

1. Work on the puzzle as a whole.
2. Start with one sub-puzzle and solve as many cells as you can, until you can’t go further (do not guess!)
3. Move on to the next sub-puzzle. Use clues from the previous sub-puzzle.
4. Repeat step 2 for that sub-puzzle.
5. Keep repeating steps 2-3-4 until you solve the whole puzzle!
6. Do not start with the center sub-puzzle. They usually have fewer clues than other sub-puzzles.

Usual classic Sudoku techniques are required to solve these puzzles: naked and hidden singles, naked and hidden subsets (pairs, triplets etc) and “row/column and box interactions”. For the hardest of puzzles X-Wing and Swordfish techniques might be needed.

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44 Comments

  1. Merry
    Posted February 13, 2006 at 11:18 pm | Permalink

    For newcomers — what are naked and hidden singles, naked and hidden subsets, etc, as mentioned above? Or where can I find out where they are — your help only tells you how to solve sudoku x puzzles, not regular ones (or samarai).

  2. Ankora
    Posted February 28, 2006 at 5:36 pm | Permalink

    Now, I´m looking for link to your discus forum. 🙂

  3. LaKena
    Posted April 17, 2006 at 5:15 am | Permalink

    I’m gonna work out this Sunday’s solution. I love a logical challenge on paper.

  4. Terry
    Posted April 18, 2006 at 5:45 pm | Permalink

    I have been looking for about an hour now and can not find the solution to the 4-14-2006 Express Lookout Weekend Samurai Sudoku puzzle. My friend has 3 of the 5 puzzles done and has an error. I was going to help her find it. Can you tell me where the solution is located. Thanks!

  5. Posted April 19, 2006 at 1:37 am | Permalink

    Terry, I’m sorry but we only post solutions for the puzzles printed in The Post. We don’t post those from The Express. That’s the deal we made.

  6. Cristina
    Posted May 2, 2006 at 8:47 pm | Permalink

    Dear DJape,

    I lost my solution to the online samuri game from April 25. Is it possible for me to get the solution again?

    Thank you,
    Cristina

  7. Posted May 4, 2006 at 1:54 am | Permalink

    My brother Mom and i have just started these puzzles and are going crazy to try and finish them. they are so addicting and fun!!!!!!!!

  8. Mary
    Posted August 24, 2006 at 12:34 pm | Permalink

    I would like to get a blank copy of the puzzle that is posted in the sunday post.

  9. Posted August 24, 2006 at 1:22 pm | Permalink

    Hi Mary,

    Sorry, we cannot show puzzles from The Washington Post on our website. You can get a blank Samurai grid here: http://www.djape.net/download/images/samuraigrid.png

    Download it, print it and copy the given numbers from the puzzle that you have.

    Good luck!

    🙂

  10. Rich
    Posted September 26, 2006 at 9:22 am | Permalink

    Thanx 4 the rules/tips that you listed. They give more than any other site has listed of any kind.It may not be needed for everyone but in the Samuarai the clues give some more help. Thanx. Rich

  11. Chris
    Posted December 18, 2006 at 10:20 pm | Permalink

    Hello. I am solving this Sunday’s (12/17) Samurai Sudoku puzzle in The Washington Post and i was wondering, is it possible to solve it without using the X-Wing or Swordfish Techniques? (it says its a 2 out of 5). Also is whats printed the post Samurai Sudoku X or Killer? And what exactly is the difference between the the three versions?

  12. Chris
    Posted December 20, 2006 at 4:06 am | Permalink

    I would still like an answer to my first question. Also at the top you said “Well – there aren’t any special tips that apply exclusively to Samurai.” well i believe i have found one that does. Well it would work for any large puzzle that overlaps in at least one nonet. It has to do with how numbers repeat because of the overlap. I can explain in detail if you want.

  13. Posted January 25, 2007 at 7:07 pm | Permalink

    Hi Chris,

    Sorry for responding this late…

    Yes, 12/17 Samurai puzzle from The Post can be solved without X-Wing and/or Swordfish.

    It requires either naked/hidden subsets OR row/column and nonet interactions. There are a couple of approaches to solving it.

    In fact, about one half of the puzzle can be solved using only naked/hidden singles.

    To answer your other question:
    – Samurai Sudoku puzzles are those that you can see in The Post every Sunday.
    – Samurai X puzzles are similar but with one additional rule: each diagonal (there are 10 diagonals in each Samurai puzzle) must contain all numbers from 1-9, just as any row/column/nonet.
    – Killer Samurai: those are completely different. You don’t have any given numbers, instead you have “cages” (fences) with a number which indicates the sum of the numbers within a cage. Don’t worry about Killer Samurai – if you are interested, you should first practice Killer Sudoku which you can find every day on my “Daily Killer” page: http://www.djape.net/killer-sudoku/

    If you have any further questions it is best to ask them in the forum: http://www.djape.net/sudoku/forum

    Have fun!

    Djape 🙂

  14. Norbert Dee
    Posted February 26, 2007 at 4:39 am | Permalink

    Can you explain or point me to a reference to explain what are naked/hidden singles or subsets. I am a new player. Thanks

  15. Posted February 26, 2007 at 10:57 am | Permalink

    Norbert Dee, you can find that in the classic sudoku techniques section: http://www.djape.net/?p=157

    djape

  16. Emma Lee
    Posted July 16, 2007 at 12:37 am | Permalink

    Hello,
    I was out of town on June 17, 2007.
    Is there any way I can get a copy of the samurai sudoku from the Washington
    Post?

    Thank you,

    Emma Lee

  17. Posted July 16, 2007 at 1:52 pm | Permalink

    Hi Emma Lee,

    Unfortunately, the answer is no. The deal with The Washington Post is to show only solutions for the puzzles and not the puzzles themselves. This is simply because those puzzles have been designed exclusively for the readers of The Post and if I showed them on my site they would be available to anyone.

    I hope you find some other puzzle on my site that you find interesting.

  18. steve
    Posted August 9, 2007 at 7:07 am | Permalink

    I do the sudoku alot with 5 others from work. I found a Samurai sudoku and made copies for the others i do them with.. we all are still working on the same Samuri sudoku for the past two weeks and none of us have been able to figure it out yet.. There ready to kill me.. HELP.. ( this samuri sudoku is only a 2 out of 5 )

  19. Royalty
    Posted August 16, 2007 at 8:19 pm | Permalink

    Hi, i’m a newcomer to this website but not to sudoku…..but i just started working on samurai sudoku puzzles…..and from what i seen so far from this website, i see there are a lot of techniques that i never knew of, when i was doing regular sudoku puzzles…i was just wondering if you had a page just explaining all the different types of techniques and their names that you can use?

  20. Janet
    Posted August 25, 2007 at 10:51 pm | Permalink

    Hi,

    I am a samurai wizard and never spend more than a leasurely hour on anything under a 4 but the last 2 puzzles (August 18, and todays, August 25) have gotten me at a total stand still with nothing more to do than start guessing and they are ‘2’. I never guess. Is someone else writing these?

    Thanks …

  21. Posted August 25, 2007 at 11:46 pm | Permalink

    Hi Janet,

    No, it’s still me creating these puzzles. 🙂 I don’t think the difficulty of the two puzzles you mention is any different from other puzzles.

    Where did you get stuck? No guessing is required, I can assure of that. Perhaps it was just your bad day? 🙂

    Good luck!

    Dj.

  22. Posted September 15, 2007 at 6:54 pm | Permalink

    I am curious to know whether a “5” rating means it’s harder than the lower ratings. I have also found that a 4 rating appears easier than a 2 rating. Can anyone tell me which is the hardest rating?

  23. Posted September 16, 2007 at 3:02 pm | Permalink

    Manny, yes, a higher number means that the puzzle is more difficult. However, the difficulty of a puzzle is a very personal thing, to some people some puzzles are easier than other, while some people would find the opposite.

    Do not pay too much attention to the indicated difficulty. Try to solve the puzzle and enjoy doing it! 🙂

    Good luck.

  24. Peter M. Smith
    Posted January 21, 2008 at 9:27 pm | Permalink

    Dear Sir,

    While attempting to solve the Samurai Sudoku (Wash. Post, Sunday 1/20/2008) I seemed to have arrived at non-unique solutions). Four of the 9×9 puzzles solve uniquely and are consistent amongst themselves. The fifth 9×9 puzzle (bottom right seems to have multiple solutions) with two non-unique rectangles for the digit pairs 54 & 89.

    My solution for the this lower right puzzle is with x=54, y=89

    192 3xx 876
    853 671 429
    746 y2y 135
    427 583 691
    368 192 547
    519 467 283
    634 y1y 752
    285 736 914
    971 2xx 368

    FYI, the center puzzle solved as
    861 234 579
    523 789 416
    479 156 238
    634 527 981
    952 861 347
    718 943 625
    386 475 192
    147 692 853
    295 318 746

    Could you please comment on the uniqueness of this Samurai puzzle,

    Thank You

    Peter M. Smith

  25. Posted January 22, 2008 at 10:44 am | Permalink

    Dear Peter, the problem is with your solution of the center puzzle. You have two 6s in the last column of the center puzzle, which, of course, is against the rules.

  26. Tiara
    Posted January 23, 2008 at 3:04 am | Permalink

    Hey… so I was looking for something to check my one of my sub-puzzle things.. so is there anyplace I can go to check my work?

  27. claudia
    Posted April 7, 2008 at 9:22 pm | Permalink

    After trying to solve one of these since january, I was finally able to solve the 3/30/08 edition in the wash Post. after working on it for over a week! I have a hard time understanding the written explainations on tips to solve. I am reminded of the Louis Armstrong Quote about What is jazz? “If you have to ask you’ll never know? That’s how I feel about x wing and sword fish,and naked triples. I think i need a live chat version of solving tips:) I just don’t understand the explainations.! anyway, I’m off to try my luck with the 4/7 edition!!!

  28. Posted April 7, 2008 at 10:20 pm | Permalink

    Claudia, X-Wing and Swordfish techniques are never needed in the puzzles that are published in The Washington Post and/or Express.

    Naked/hidden triplets might occasionally come about and they can be difficult to spot, but with a little practice you should be fine.

    The best advice I can give – practice those advanced techniques (such as naked/hidden subsets) on regular Sudoku puzzles and then move on to the Samurai puzzles.

    Good luck and let us know how you’re doing! 🙂

  29. Becky Rice
    Posted June 30, 2008 at 3:05 am | Permalink

    How do you determine the difficulty, example 0-5? Have you ever had a 0? Is 5 the most difficult?

  30. Dennis F.
    Posted September 30, 2008 at 2:05 pm | Permalink

    Has anyone solved the puzzle from Wash. Post 9/28/08. I am stuck on the top right boxes. What did you get?

  31. Posted September 30, 2008 at 2:59 pm | Permalink

    Dennis, you can find the solution on the http://www.djape.net/solutions/ solutions page.

  32. Alex
    Posted December 2, 2008 at 10:42 pm | Permalink

    ok so i have to do a samurai sudoku for extra credit in school. but i dont get the directions AT ALL!!! i need help to solve it!!

  33. Posted December 3, 2008 at 2:30 am | Permalink

    Alex, the best place to get an advice is in the forum: http://www.djape.net/sudoku/forum

  34. Lynette Maria Entzian
    Posted June 16, 2009 at 2:47 am | Permalink

    I am looking for the solution for the Samurai Sudoku puzzle from the Washington Post for Sunday May 10, 2009. Do you know how I can find it?

    Thanks,
    Lynette

  35. Posted June 16, 2009 at 7:48 am | Permalink

    Hi Lynette,

    The solution you are looking for is in the archive:
    http://www.djape.net/gallery.php?file=Washington%20Post%20Solutions%202009/May/

    Hope you’ll find it.

  36. Ivan Soto
    Posted April 9, 2011 at 11:15 pm | Permalink

    The samurai sudoku published in The Washington Post of April 10, 2011 has no solution. Why bother to publish sudokus with such poor quality control?
    -9—4-6—–5-1—8-
    -678–4——-3–961-
    —-6———–7—-
    35—2–1—4–6—92
    —1-62——-27-1—
    4–7—9—–6—5–3
    —-9—-6-7—-3—-
    4–7—9—–6—5–3
    —-9—-6-7—-3—-
    –9–3—3-9—5–9–
    -4—8———9—6-
    ——4–7-6–9——
    ——–8—2——–
    ——2–4-8–6——
    -7—9———5—7-
    –1–7—1-4—8–4–
    —-2—-5-3—-4—-
    6–7—8—–4—3–2
    —3-56——-81-2—
    93—8–4—9–4—87
    —-3———–3—-
    -459–1——-6–875-
    -8—1-6—–8-6—2-

  37. Posted April 12, 2011 at 3:57 am | Permalink

    Ivan, you will have to elaborate on that comment.

    It has never happened that a puzzle I published had anything but a unique solution. So, if you claim that this one doesn’t, I ask you to have a look at the archive where there is a solution to this puzzle.

    http://www.djape.net/gallery.php?file=Washington%20Post/

    Cheers,
    Djape

  38. Ivan Soto
    Posted April 15, 2011 at 10:54 am | Permalink

    Well, I can’t reproduce the solution I had. I no longer have the puzzle as originally published by the Washington Post and the copy I received from you, Djape, does have a solution. Either I overlooked something when I went through my solution or else the copy I received from you does not exactly replicate the published puzzle.

    The benefit of my doubt should go to the publishing procedure and so I withdraw the comment about poor quality control.

    Thanks for your follow-up.

  39. Carl Knoettner
    Posted April 17, 2011 at 3:26 am | Permalink

    How to Play instructions “Don’t focus on completely one grid at a time.” should read “Don’t focus on completing one grid at a time.”

    (Please just send me an email. You don’t need to publish it on the website. I just wanted to make to Washington Post directions better.)

  40. Bil Greene
    Posted January 29, 2012 at 3:19 pm | Permalink

    It would make your puzzles easier to work with if you could put up a grid so that we could print if off. That would hopefully give us a bigger space in which to put our possible numbers in the squares and when our squares got to messy we could then print off a new one.

    Thanks

    • Posted January 30, 2012 at 2:26 am | Permalink

      Bil, thank you for your comment.

      If you need a blank grid for Samurai Sudoku or Diagonal Sudoku (which is also good for Killer Sudoku), you can find all of them here: blank grids.

  41. Kenneth Laun
    Posted December 1, 2012 at 1:30 pm | Permalink

    There appears (at least to me) to be a second solution to the Sunday, 11-25 puzzle from the Washington Post. All changes are in the center three columns of the center section. Below the 5-7-1, use 9-6-8, next 4-2-3, then all the same as you had until the penultimate line of three which would be 6-3-9 and the last of 2-8-4. Ken Laun 703-978-1390 or see below.

    • Posted December 2, 2012 at 1:36 am | Permalink

      Kenneth, please post your other solution in this format:

      123456789 123456789
      123456789 123456789
      123456789 123456789
      123456789 123456789
      123456789 123456789
      123456789 123456789
      123456789123123456789
      123456789123123456789
      123456789123123456789
      123456789
      123456789
      123456789
      123456789123123456789
      123456789123123456789
      123456789123123456789
      123456789 123456789
      123456789 123456789
      123456789 123456789
      123456789 123456789
      123456789 123456789
      123456789 123456789

      Then I will tell you if you are right or wrong. 🙂

  42. Neil A Spangler
    Posted May 29, 2017 at 3:57 pm | Permalink

    Folks, I seriously question your grading system. For instance, your 4’s and 5’s are really no problem but a 3 gives e
    me fits. What’s going on here?

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